B6304 'Rotating' Valves - Technical Question

Stan, A retired Engine designer and myself have been reading the same post as you,it apparently applies to both five and six cylinder engines,as far as we can make out it has more to to with the priming of the tappets,in that if the engine is only run momenterily the tappets fill in such a way as to prevent the valve closing!?!? I have not noticed a great number of 850's with lack of compression and many are used as family hacks with associated short journeys,then again perhaps I have missed the posts. Mike

I dont believe the valves rotate at all . where did this theory come from? The valve stem at the top is located by the collets wedging the valve stem to the top spring cap with quite a tight grip how can this "rotate" as the valve spring cap and valve are virtualy as one when clamped up with the spring pressure ? The cam followers themselves can roatate but not the valves themselves ... Anyone will find when they dismantle a valve spring and remove the top spring seat and collets that there is no sign of movment which would be shown as polished collets or wedge seat in the spring cap .

An interesting subject !! I agree with all said, however in earlyer designed engines where the cam pushed followers on to pushrod then thru a rocker arm to valve, the cam was "Off set" a few thou to actualy rotate the follower so the pushrod would turn to , this was a way the oil could get to all places and to stop wear in one point on follower pushrod etc,, With OHC engines offsetting the cam would probably result in more wear due to points above,, Cheers Bateye,